1. The Field of the Invention
This invention is in the field of catheters, including catheterization systems employing occluding wires for use in perfusion catheters.
2. The Relevant Technology
Perfusion catheters have become popular in recent years for use in anesthetizing tissues at an insertion site of a catheter and for treating clotted blood vessels, among other uses. Perfusion catheters typically feature a cannula having infusion holes in a wall thereof for enabling fluid to flow through the wall onto the sensitive tissues of a patient or adjacent an area in which the practitioner has discovered a clot. By positioning the holes of the catheter adjacent the area to be treated, a fluid may be applied to the area, thereby diffusing the clot or anesthetizing the tissues. Once the catheter is positioned at the site of the clot, for example, a thrombolytic fluid capable of dissolving the clot, such as urokinase or streptokinase, is delivered to the site of the clot.
Typical perfusion catheter assemblies comprise a catheter, a fluid supply port, and a hemostasis valve coupled to a proximal end of the catheter which substantially prevents fluid from flowing out a proximal end of the catheter assembly during use. Generally, the distal insertion end of the catheter assembly is open and must therefore be occluded prior to irrigating a liquid from a fluid source through the fluid supply port and into an infusion length of the catheter, where the infusion holes are located. Occlusion of the distal opening of the catheter assembly may be accomplished by inserting an occluding wire through the valve of the assembly and then inserting the wire further along the length of the catheter.
The occluding wire substantially seals the distal end of the infusion catheter during use in order to facilitate spray distribution through the holes. The occluding wire typically includes a wire body portion and a distal sealing ball portion. The sealing ball portion forms a substantially liquid-tight seal at the distal end of the catheter, thereby forcing liquid located proximal to the seal out of the infusion holes of the catheter. Because the inner diameter of the catheter is typically larger than the diameter of the wire body portion of the occluding wire, there is ample space within the infusion catheter for the passage of a liquid out of the infusion holes.
In certain catheters, such as typical 5 French catheters, the inner diameter of the catheter is reduced to a narrow neck at the distal end of the catheter. The sealing ball portion of the occluding wire seats against the inner, narrow neck wall portion of the catheter when inserted into the distal end and thereby substantially occludes the distal opening of the catheter. Consequently, substantially any liquid forced through the catheter is caused to exit through the infusion holes rather than through the opening.
In other catheters, such as typical 4 French catheters, the inner diameter of the catheter is constant throughout the catheter, but the diameter of the occluding ball is configured to substantially match the inner diameter of the catheter. Thus, the practitioner slides the occluding ball to the distal tip, thereby substantially occluding the passageway of the catheter and forcing fluid to flow out of the side perfusion holes proximal to the occluding ball.
When the distal end of the occluding wire is positioned in the catheter, the proximal end of the occluding wire is generally positioned within the hemostasis valve of the catheter assembly. The valve temporarily prevents the occluding wire from moving until the occluding wire is grasped, pushed, or otherwise moved by a practitioner. Consequently, it is generally possible to intentionally or accidentally slide the occluding wire with respect to the catheter, particularly when an adjustable valve is loosened.
Thus, one ramification of present occluding wire and catheter designs is that during use of the catheter system, the proximal end of the occluding wire is generally slidably movable with respect to the hemostasis valve. In addition, the proximal end of the occluding wire generally extends from the proximal end of the catheter assembly and remains exposed to the environment. This dynamic results in a variety of different complications.
For example, the occluding wire can be inadvertently inserted too far distally through the catheter or retracted proximally from a desired position in the catheter. Such inadvertent insertion of the occluding wire may occur when a practitioner accidentally contacts the proximal end of the wire or may be caused by an infusion of fluid under a significant amount of pressure. Such inadvertent actions can cause the occluding wire to lose its occluding effect, for example, by causing the occluding ball to exit the distal opening of the catheter or by inadvertently retracting the ball proximally to a distal set of holes, thereby occluding the fluid supply to the distal set of holes.
In addition to the aforementioned drawbacks associated with typical catheterization systems employing occluding wires, other elongate bodies, such as catheters and guidewires can also be inadvertently displaced from or moved within hemostasis valves.
There is therefore a need in the art for an improved catheterization system for percutaneous catheterization of a blood vessel. More specifically, there is a need in the art for a catheterization system having an improved occluding wire.